The molecules of the title compound s(5-acetylamino-1,3,4-thiadiazole-
2-sulfonyl)amine dihydrate, C8H9N7O6S4.2H2O (1)] consist of two nearly
planar acetylaminothiadiazolesulfonyl units which are parallel to one
another. Coplanarity of the acetylamino groups and the thiadiazole ri
ngs is achieved by pi-electron delocalization over these groups and by
non-bonded S...O interactions [S1...O1 2.667 (4), S1'...O1' 2.661 (4)
angstrom].